Various solutions exist for improving the aerodynamic properties of moving bluff-shaped ground vehicles (i.e., non-streamlined shaped vehicles such as cars, trains, trucks, land-carried intermodal containers, etc.). When the ground vehicle travels, the bluff-shaped body may produce considerable aerodynamic resistance. Typically, a region of separated airflow occurs over a large portion of the surface of the bluff body. This may result in a high aerodynamic drag force and a large wake region. Airflow around the vehicle typically exhibits unsteadiness, such as periodic vortex formation and shedding. To reduce the known drawbacks of the vehicle shape, airflow control systems may be used to improve the aerodynamics.
Many current aerodynamic drag reduction devices are based on modifying the form of the vehicle body, its geometry, its surfaces or the type of body material to reduce the drag force exerted on the vehicle body. Other current aerodynamic drag reduction systems use pneumatic aerodynamic control to reduce flow separation. Typically, externally supplied compressed air is used to produce an additional flow of air through blowing outlets, such as openings on the vehicle. These systems use a compressed air plenum for all of the blowing outlets. The compressed air is discharged from the blowing outlets to reduce flow separation and reduce drag. Because the systems use a compressed air plenum for all blowing outlets, the system is connected to a robust air supply resource, such as the vehicle air supply/generation system or to a mountable compressor that is independent of the vehicle. The dependency on compressed air may substantially increase the energy requirements of the system, and may increase the size and/or weight of the system at the expense of the carrying capacity of the vehicle.